This proposal seeks support for a study of change and stability in personality traits using unique longitudinal data collected from 1975 to 1995. The primary goals are to: 1) estimate the individual differences in trait change over time using novel methods that capture intraindividual change, and 2) predict this intraindividual change with health, stress, and sociodemographic variables. Longitudinal data from the Normative Aging Study (NAS) will be used. The NAS is a long-term study of aging process in older men, mostly veterans. These data are exceptional in that repeated measurements go back 20 years for the personality traits under consideration (extraversion and neuroticism) and over 30 years for the health measures. Previous research on trait change has almost entirely focused on mean-level or correlational stability. We argue that only intraindividual techniques can accurately depict personality change. Most personality theory focuses on change or stability at the person level. However, nearly all personality research has focused on change or stability at the sample level. Only techniques which allow the modeling of intraindividual (or ipsative) change can reconcile this wide disparity between theory and research. We will accomplish the first goal via the estimation of individual growth-curves for each participant on two major personality traits, extraversion and neuroticism. Both linear and nonlinear growth-curves will be estimated for short-term (7-year) and long-term (20-year) time frames. To accomplish the second goal, the individual growth-curves estimated in the first stage will be used as dependent variables in a second stage of analysis. This will permit the examination of potential predicators of personality change such as birth cohort, retirement status, death of spouse, and onset of physical illness. We hypothesize that the estimation of individual trajectories will show a mix of stability and change. We further expect our chosen potential predicators to elucidate the processes that lead to both change and stability, especially contextual variables such as life stress and retirement. Use of this approach will shed new light on the old question of personality change in adulthood, and how such change is related to important life events, sociodemographic characteristics, and health.